Cathode ray tube



June 26, 31934., H. HALBERSTDT CATHODE RAY TUBE Filed Oct. 10 1951 Patented June 26, 1934 UNITED STATES PATENT OFFiCE CATHODE RAY TUBE Heinrich Halberstadt,

Hamburg,

Fuhlsbuttel,

Germany, assigner to C. H. F. Muller Aktiengesellschaft, Hamburg, Germany 5 Claims.

In operating cathode ray tubes, particularly those used for physiological researches or treatment of ill persons, it is an essential requirement that, during operation, the cathode ray window should be at ground potential. The well known cathode ray tubes cannot be used therefore without additional means for the purpose referred to. These cathode ray tubes, in which the anode and the Window are brought jointly to ground potential and 'in which only the cathode is connected to the source of high voltage, require specially designed high voltage apparatus. In order that it may be possible to operate at very high voltages it is preferable that both poles of the high voltage apparatus should be insulated from ground.

The two disadvantages described are obviated by the device according to the invention, as the cathode ray tube here described permits of both poles being insulated from ground and nevertheless has a window for the exit of the rays that may be at ground potential. Before the cathode rays pass through the window they rush through a Faraday cage arranged behind the apertured anode. On their way from the cathode to the anode the electrons acquire their full speed and then fiow with undiminished speed through the described space behind the anode which is closed by the Lenard window.

Experiments have shown that the yield of rays passing out through the window, provided for the exit of the rays, is materially increased when the anode is connected to the grounded window through a high resistance. A suitable adjustment of said resistance ensures a more favourable distribution of the voltage in the discharge path, which may account for the improved results.

In order that the invention may be clearly understood and readily carried into effect reference may be had to the accompanying drawing wherein Fig. l is a view, partly in section, of a cathode-ray tube embodying the invention and Fig. 2 is a similar view of a modication.

Figure 1 shows a cylindrical cathode ray tube having a wall 1 preferably of glass. The anode is formed by a metal ring 2 sealed to the glass wall l and also forming part of the wall of the vessel. The cathode 3 is surrounded by a suitably shaped focussing device which assists in properly directing the cathode rays towards the window provided for the exit of the rays. The Faraday-cage is limited by a substantially cylindrical hollow body 4 which may be electrically connected to the Lenard window 5. Preferably, a high ohmic resistance 6 may be connected between the ground and the anode. Said resistance is made regulable to a desired extent and may be formed by an ohmic resistance, an alternating current resistance or a high vacuum resistance. The variable characteristic of the resistance is particularly convenient in connection with a high vacuum resistance having an incandescent cathode. In this case it is possible, by controlling the supply of heat to the incandescent cathode of said resistance, to adjust to any desired intensity the yield of the cathode ray beam,

A further form of construction of the cathode ray tube described is shown in Figure 2. As in the construction shown in Fig. 1, the glass wall 7 is interrupted by a metal body 8 sealed to it, but 70 a cylindrical or cup-shaped hollow body 9 acts as the anode. The cathode l0 extends into the anode which is also provided with an annular flange 11 which projects into a Faraday cage 12 closed at its lower end by the window for the exit oi the rays.

What I claim is:

1. A cathode-ray tube comprising an evacuated envelope consisting at least partly of glass and having a Lenard window for the exit of rays, a cathode member therein, an anode member mounted in spaced relation to said cathode member to form a discharge gap, said anode having an aperture permitting the passage of eleotrons emitted by said cathode member, a tubular metal member mounted in line with said aperture and forming a shielded eldless space through which travel the electrons passing through the said aperture, said tubular member being open at its end adjacent the anode member and disposed between said anode member and said window, and glass portions of the envelope insulating said tubular member for high tension from the anode and from the cathode members.

2. A cathode-ray tube comprising an evacuated envelope consisting of two glass portions separated by an annular metal portion having its rims sealed to the glass portions by fusion, said annular portion having an apertured partition separating the envelope into two chambers, said chambers communicating through the aperture in said partition, a source of electrons disposed in one of said chambers in front of the aperture and carried by a glass portion which insulates it for high tension from the annular portion, a tubular metal member disposed in the second chamber and in spaced relationship with said partition and opposing said aperture and extending throughout the full length of the second chamber, said tubular member being insulated by the envelope from the anode, and a Lenard-window closing the outer end of the tubular member.

3. A cathode-ray tube comprising an evacuated envelope consisting of two glass portions separated by an annular metal portion having its rims sealed to the glass portions by fusion, a cupshaped anode member coaxially mounted Within said annular portion, means for supporting said anode member from one end of the envelope, a

cathode adapted to be heated to ineandescence,y

shaped anode mounted Within said annular portion and a cathode mounted within said anode, a lateral metal extension of said annular portion, a Lenard-Window closing said extension, said anode having a lateral aperture permitting electrons emitted by the cathode to pass into the said lateral extension and a metal flange surrounding said aperture and extending therefrom into the said lateral extension.

5. A cathode-ray tube comprising an evacuated envelope, cathode and anode members mounted therein, said envelope having a conductive window for the exit of the cathode rays and a conductive shielding member substantially enclosing the path of the beam of rays from said anode member to said Window, said shielding member being insulated from said anode member, and a connection for said window and shielding member adapted to be grounded whereby said Window and shielding member can be maintained at ground potential.

HEINRICH HALBERSTADT. 

